yugioh light and darkness dragon deck *** *** QUARTER CENTURY SECRET RARE MP24-EN024 YUGIOH! YU-GI-OH! - Light and Darkness

It also allows you to fight through very complex stacks or counter wars

Previously, the graveyard rarely affected gameplay, butOdyssey's cards forced players to constantly keep track of both graveyards at all times

Although it doesn't directly ramp you, it essentially acts as a land for just 1 mana

As for answering your original question, @fourthstartcg did a good job breaking it down

It helps save money on fees

Forcing each player to shuffle their entire discard piles back into their decks, Lysandre's Trump Card effectively eliminated the possibility that a player would run out of cards, which would otherwise mean victory for their opponent